This research project will evaluate the role of early-life health conditions in affecting the risk of adult cardiovascular and cerebrovascular disease mortality. Evaluation of such long-term health linkages is complicated by a) the paucity of data containing information on both early-life health conditions and adult vascular health and b) biases generated by the association of early-life health conditions with other factors affecting adult vascular health that are not observed by the researcher. The proposed research will use the sudden deterioration in fetal health caused by widespread maternal infection during the 1918 influenza pandemic to assess the long-term effect of fetal health on adult mortality risk. This research will be conducted using the 1980 National Longitudinal Mortality Study, which contains detailed information on adult health and demographic characteristics, and permits linkage to fetal health during the 1918 influenza pandemic. In addition to constituting demanding test of the "fetal origins" hypothesis, the proposed research will assess the extent to which the dramatic decrease in cardiovascular disease mortality rates over the last thirty years can be attributed to the substantial improvements in fetal andinfant health over the first half of the 20th Century.